233 lines
7.3 KiB
Diff
233 lines
7.3 KiB
Diff
From 078ced30af696b52a450a016a16eb47499d68117 Mon Sep 17 00:00:00 2001
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From: Linus Walleij <linus.walleij@linaro.org>
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Date: Wed, 8 Jul 2020 14:25:36 +0200
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Subject: [PATCH 2/5] net: dsa: tag_rtl4_a: Implement Realtek 4 byte A tag
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This implements the known parts of the Realtek 4 byte
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tag protocol version 0xA, as found in the RTL8366RB
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DSA switch.
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It is designated as protocol version 0xA as a
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different Realtek 4 byte tag format with protocol
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version 0x9 is known to exist in the Realtek RTL8306
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chips.
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The tag and switch chip lacks public documentation, so
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the tag format has been reverse-engineered from
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packet dumps. As only ingress traffic has been available
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for analysis an egress tag has not been possible to
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develop (even using educated guesses about bit fields)
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so this is as far as it gets. It is not known if the
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switch even supports egress tagging.
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Excessive attempts to figure out the egress tag format
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was made. When nothing else worked, I just tried all bit
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combinations with 0xannp where a is protocol and p is
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port. I looped through all values several times trying
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to get a response from ping, without any positive
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result.
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Using just these ingress tags however, the switch
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functionality is vastly improved and the packets find
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their way into the destination port without any
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tricky VLAN configuration. On the D-Link DIR-685 the
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LAN ports now come up and respond to ping without
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any command line configuration so this is a real
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improvement for users.
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Egress packets need to be restricted to the proper
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target ports using VLAN, which the RTL8366RB DSA
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switch driver already sets up.
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Cc: DENG Qingfang <dqfext@gmail.com>
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Cc: Mauri Sandberg <sandberg@mailfence.com>
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Reviewed-by: Andrew Lunn <andrew@lunn.ch>
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Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
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Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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include/net/dsa.h | 2 +
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net/dsa/Kconfig | 7 +++
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net/dsa/Makefile | 1 +
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net/dsa/tag_rtl4_a.c | 130 +++++++++++++++++++++++++++++++++++++++++++
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4 files changed, 140 insertions(+)
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create mode 100644 net/dsa/tag_rtl4_a.c
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--- a/include/net/dsa.h
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+++ b/include/net/dsa.h
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@@ -42,6 +42,7 @@ struct phylink_link_state;
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#define DSA_TAG_PROTO_8021Q_VALUE 12
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#define DSA_TAG_PROTO_SJA1105_VALUE 13
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#define DSA_TAG_PROTO_KSZ8795_VALUE 14
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+#define DSA_TAG_PROTO_RTL4_A_VALUE 17
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enum dsa_tag_protocol {
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DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE,
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@@ -59,6 +60,7 @@ enum dsa_tag_protocol {
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DSA_TAG_PROTO_8021Q = DSA_TAG_PROTO_8021Q_VALUE,
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DSA_TAG_PROTO_SJA1105 = DSA_TAG_PROTO_SJA1105_VALUE,
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DSA_TAG_PROTO_KSZ8795 = DSA_TAG_PROTO_KSZ8795_VALUE,
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+ DSA_TAG_PROTO_RTL4_A = DSA_TAG_PROTO_RTL4_A_VALUE,
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};
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struct packet_type;
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--- a/net/dsa/Kconfig
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+++ b/net/dsa/Kconfig
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@@ -80,6 +80,13 @@ config NET_DSA_TAG_KSZ
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Say Y if you want to enable support for tagging frames for the
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Microchip 8795/9477/9893 families of switches.
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+config NET_DSA_TAG_RTL4_A
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+ tristate "Tag driver for Realtek 4 byte protocol A tags"
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+ help
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+ Say Y or M if you want to enable support for tagging frames for the
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+ Realtek switches with 4 byte protocol A tags, sich as found in
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+ the Realtek RTL8366RB.
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+
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config NET_DSA_TAG_QCA
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tristate "Tag driver for Qualcomm Atheros QCA8K switches"
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help
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--- a/net/dsa/Makefile
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+++ b/net/dsa/Makefile
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@@ -10,6 +10,7 @@ obj-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa
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obj-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
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obj-$(CONFIG_NET_DSA_TAG_GSWIP) += tag_gswip.o
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obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
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+obj-$(CONFIG_NET_DSA_TAG_RTL4_A) += tag_rtl4_a.o
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obj-$(CONFIG_NET_DSA_TAG_LAN9303) += tag_lan9303.o
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obj-$(CONFIG_NET_DSA_TAG_MTK) += tag_mtk.o
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obj-$(CONFIG_NET_DSA_TAG_QCA) += tag_qca.o
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--- /dev/null
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+++ b/net/dsa/tag_rtl4_a.c
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@@ -0,0 +1,130 @@
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+// SPDX-License-Identifier: GPL-2.0
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+/*
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+ * Handler for Realtek 4 byte DSA switch tags
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+ * Currently only supports protocol "A" found in RTL8366RB
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+ * Copyright (c) 2020 Linus Walleij <linus.walleij@linaro.org>
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+ *
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+ * This "proprietary tag" header looks like so:
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+ *
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+ * -------------------------------------------------
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+ * | MAC DA | MAC SA | 0x8899 | 2 bytes tag | Type |
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+ * -------------------------------------------------
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+ *
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+ * The 2 bytes tag form a 16 bit big endian word. The exact
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+ * meaning has been guessed from packet dumps from ingress
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+ * frames, as no working egress traffic has been available
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+ * we do not know the format of the egress tags or if they
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+ * are even supported.
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+ */
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+
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+#include <linux/etherdevice.h>
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+#include <linux/bits.h>
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+
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+#include "dsa_priv.h"
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+
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+#define RTL4_A_HDR_LEN 4
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+#define RTL4_A_ETHERTYPE 0x8899
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+#define RTL4_A_PROTOCOL_SHIFT 12
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+/*
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+ * 0x1 = Realtek Remote Control protocol (RRCP)
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+ * 0x2/0x3 seems to be used for loopback testing
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+ * 0x9 = RTL8306 DSA protocol
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+ * 0xa = RTL8366RB DSA protocol
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+ */
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+#define RTL4_A_PROTOCOL_RTL8366RB 0xa
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+
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+static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb,
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+ struct net_device *dev)
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+{
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+ /*
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+ * Just let it pass thru, we don't know if it is possible
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+ * to tag a frame with the 0x8899 ethertype and direct it
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+ * to a specific port, all attempts at reverse-engineering have
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+ * ended up with the frames getting dropped.
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+ *
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+ * The VLAN set-up needs to restrict the frames to the right port.
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+ *
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+ * If you have documentation on the tagging format for RTL8366RB
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+ * (tag type A) then please contribute.
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+ */
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+ return skb;
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+}
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+
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+static struct sk_buff *rtl4a_tag_rcv(struct sk_buff *skb,
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+ struct net_device *dev,
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+ struct packet_type *pt)
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+{
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+ u16 protport;
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+ __be16 *p;
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+ u16 etype;
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+ u8 *tag;
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+ u8 prot;
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+ u8 port;
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+
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+ if (unlikely(!pskb_may_pull(skb, RTL4_A_HDR_LEN)))
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+ return NULL;
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+
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+ /* The RTL4 header has its own custom Ethertype 0x8899 and that
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+ * starts right at the beginning of the packet, after the src
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+ * ethernet addr. Apparantly skb->data always points 2 bytes in,
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+ * behind the Ethertype.
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+ */
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+ tag = skb->data - 2;
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+ p = (__be16 *)tag;
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+ etype = ntohs(*p);
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+ if (etype != RTL4_A_ETHERTYPE) {
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+ /* Not custom, just pass through */
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+ netdev_dbg(dev, "non-realtek ethertype 0x%04x\n", etype);
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+ return skb;
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+ }
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+ p = (__be16 *)(tag + 2);
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+ protport = ntohs(*p);
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+ /* The 4 upper bits are the protocol */
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+ prot = (protport >> RTL4_A_PROTOCOL_SHIFT) & 0x0f;
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+ if (prot != RTL4_A_PROTOCOL_RTL8366RB) {
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+ netdev_err(dev, "unknown realtek protocol 0x%01x\n", prot);
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+ return NULL;
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+ }
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+ port = protport & 0xff;
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+
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+ skb->dev = dsa_master_find_slave(dev, 0, port);
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+ if (!skb->dev) {
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+ netdev_dbg(dev, "could not find slave for port %d\n", port);
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+ return NULL;
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+ }
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+
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+ /* Remove RTL4 tag and recalculate checksum */
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+ skb_pull_rcsum(skb, RTL4_A_HDR_LEN);
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+
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+ /* Move ethernet DA and SA in front of the data */
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+ memmove(skb->data - ETH_HLEN,
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+ skb->data - ETH_HLEN - RTL4_A_HDR_LEN,
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+ 2 * ETH_ALEN);
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+
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+ skb->offload_fwd_mark = 1;
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+
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+ return skb;
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+}
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+
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+static int rtl4a_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
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+ int *offset)
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+{
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+ *offset = RTL4_A_HDR_LEN;
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+ /* Skip past the tag and fetch the encapsulated Ethertype */
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+ *proto = ((__be16 *)skb->data)[1];
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+
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+ return 0;
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+}
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+
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+static const struct dsa_device_ops rtl4a_netdev_ops = {
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+ .name = "rtl4a",
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+ .proto = DSA_TAG_PROTO_RTL4_A,
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+ .xmit = rtl4a_tag_xmit,
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+ .rcv = rtl4a_tag_rcv,
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+ .flow_dissect = rtl4a_tag_flow_dissect,
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+ .overhead = RTL4_A_HDR_LEN,
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+};
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+module_dsa_tag_driver(rtl4a_netdev_ops);
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+
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+MODULE_LICENSE("GPL");
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+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL4_A);
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